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Fix your CalSpa hot tub (error code SF)

Posted on January 23, 2016July 25, 2021 by Sid

So, I was going to relax in my spa the other day when I saw it would trip over and flash “SF” on the control panel. Here is what I did to fix it.

SF stands for safety Suction Failure. It comes up when your hot tub doesn’t suck. Typically when something doesn’t suck, it’s a good thing. But here – it’s a problem! Water can’t be sucked into the water pump, typically due to blockages. Obvious visual checks showed no blockages on any inlets. Hmm.

Before the next step – TURN OFF THE HOT TUB CIRCUIT BREAKER. Don’t die because your hot tub doesn’t suck. THAT would suck.

Next, I opened the side panel and disconnected the safety suction from the controller motherboard. It’s the black/red wire  with the brown header I’m holding below.

calspa-safety-suction-motherboard

There is (supposedly) another check on the heater so this is redundant and it was for a quick test anyway. Turning the circuit breaker back on and turning the hot tub jets to full, nothing tripped this time. Awesome! So definitely the safety suction unit/sensor.

The safety suction unit has a grey wire coming out and going to the control unit. It also has a blue rubber cover.

calspa-safety-suction-pipe

If you gently pry the blue rubber cover off, you can detach the two wires and unscrew the entire safety suction unit – which stick 90 degrees off the inlet pipe. Note that if you do unscrew it fully you’ll have a little fountain at that point and it will eventually drain your hot tub. It’s quite low pressure, so you can just screw back your new (or old) safety suction sensor without necessarily draining the entire hot tub.
In my case, I put the old non working unit back but disconnected it from the main board. I’ve ordered a new part online (Amazon). As you can see, I needed part # VM12540E-250WI

calspa-safety-suction-partnumber

I’ll update this post when I have the replacement part and have installed it next week.

UPDATE: I got the replacement part and installed it. All good.

9 thoughts on “Fix your CalSpa hot tub (error code SF)”

  1. Cheri says:
    April 23, 2018 at 5:00 pm

    Where do I find the update?

    Reply
    1. sidshetye says:
      April 23, 2018 at 9:49 pm

      Updated it but it’s pretty anti-climactic …

      Reply
  2. Kevin says:
    August 14, 2019 at 5:33 pm

    These things are a pita and useless
    Do yourself a favor unplug them from main board and save the money and aggravation

    Reply
    1. Dwane says:
      April 5, 2020 at 10:09 am

      Will it hurt to unplug the pressure switch for your California spa hot tub

      Reply
  3. Dwane says:
    August 23, 2019 at 7:26 pm

    Thanks for your all your help

    Reply
  4. Dwane says:
    April 5, 2020 at 10:10 am

    Is it necessary to have the pressure switch on the California hot tub or can I unhook him

    Reply
    1. Sid says:
      April 23, 2020 at 5:13 pm

      It’ll “work” but it’s a safety feature to switch things off in case of clogs or no/low water. So while it would work, I would buy a new pressure switch and replace it in a day or two.

      Reply
  5. Dwane Blevens says:
    March 27, 2021 at 11:21 am

    I put two new pressure switch is on and I’m still getting that 5F code can you tell me where the black wire goes and the red wire top or bottom I put black on top.

    Reply
    1. Sid says:
      July 25, 2021 at 9:32 am

      Since it’s a switch, I don’t think it really matters on the red or black being up or down. When the switch closes, it’s a closed circuit. Seems like in your case the error code is due to another reason.

      Reply

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